Speaking Of P-47s And Big Props

Jack Cook · **Posted:** Wed Feb 20, 2008 2:59 pm

P-47D 63rd FS 56th FG 1944

51fixer · **Posted:** Wed Feb 20, 2008 3:12 pm

That is a Hamilton Standard prop on the front. Solid Aluminum blades as opposed to the Curtis Electric's hollow steel. Ham Std uses engine oil from the engine to operate the prop mechanism through a prop governor. The Curtiss Elect uses electric power regulated by a prop governor and sent to an electric motor mounted in front of the blades to change the pitch of the blades.
Rich

Jack Cook · **Posted:** Wed Feb 20, 2008 3:21 pm

Quote:

That is a Hamilton Standard prop on the front. Solid Aluminum blades as opposed to the Curtis Electric's hollow steel. Ham Std uses engine oil from the engine to operate the prop mechanism through a prop governor. The Curtiss Elect uses electric power regulated by a prop governor and sent to an electric motor mounted in front of the blades to change the pitch of the blades.

and the blades have a different decals on them!!! :idea:

51fixer · **Posted:** Wed Feb 20, 2008 4:06 pm

Jack Cook wrote:

Quote:

That is a Hamilton Standard prop on the front. Solid Aluminum blades as opposed to the Curtis Electric's hollow steel. Ham Std uses engine oil from the engine to operate the prop mechanism through a prop governor. The Curtiss Elect uses electric power regulated by a prop governor and sent to an electric motor mounted in front of the blades to change the pitch of the blades.

and the blades have a different decals on them!!! :idea:

DUH!
Thats how I can tell them apart

Rich

Jack Cook · **Posted:** Wed Feb 20, 2008 4:30 pm

Here's the comparison shot!
The scholors among us will note the different decals :shock:

b29flteng · **Posted:** Wed Feb 20, 2008 5:53 pm

Note the Curtiss Electric also has blade cuffs at the base of each blade to improve engine cooling.

marine air · **Posted:** Wed Feb 20, 2008 9:58 pm

I was at Lackland AFB a couple of weeks ago and had the opportunity to spend a day looking at all the airplanes on the parade field. My pilot buddy and I were talking about the rarity of the propellors on the F-82E Twin Mustang, and we were trying to guess how they might have been made. We also looked at the P-51H, P-63, P-47N, the B-29A, and the T-28A with it's original two bladed Aeroproducts prop.
How were those hollow steel props made? It looked to us like a large single piece of steel(per blade) had been superheated and folded at the leading edge of the blade and then the two ends welded at the backside of the trailing edge of each blade. You could feel a ridge when running your finger down the edge. The back side being slightly shorter than the face of the blade.
Does anyone have any factory photos of how these were actually made?

bdk · **Joined:** Sun May 02, 2004 1:16 am **Posts:** 11324

I think the two halves were extrusions formed and then welded together around the perimeter. There is a spar in there too y'know.

gregv · **Posted:** Wed Feb 20, 2008 10:10 pm

b29flteng wrote:

Note the Curtiss Electric also has blade cuffs at the base of each blade to improve engine cooling.

I never knew what the cuffs were for, but that makes a lot of sense. Any idea why P-51D's had cuffs as well? Something to do with reducing turbulence maybe?

greg v.

visaliaaviation · **Joined:** Mon Jul 03, 2006 2:01 pm **Posts:** 353

IIRC, the primary reason for Mustang's cuffs is to improve air intake at chin intake and to augment coolant radiator while on ground.Tthat said, another obvious reason is to improve prop efficiency by fairing what would normally be just a round club section, close to the spinner.

According to an article (written by HS engineers) that appeared in 1946 Aeroplane Monthly, Hamilton Standard reverted to cuffless props on late P-51D's, not because of a shortage of cuffed units, but rather for aerodynamic reasons. It seems the cuffs, when at full pitch represented detrimental side area forward of the CG which could cause high speed stability proplems and loss of control.

An interesting aside, when the cuff is removed from a 'Cuffed HS blade, the shank ibeneath is not round, but rather rectangular. The cuflless HS with square tips is round(??!!).

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